1. Field of the Invention
The present invention relates to a regenerative refrigerator that uses a high pressure coolant gas supplied from a compressor to generate Simon expansion, and stores the cold using a regenerator, thereby generating the cryogenic cold.
2. Description of the Related Art
A regenerative refrigerator of displacer type causes a displacer to reciprocate in a cylinder and expands a coolant gas in an expansion space and generates the cold in this process. A regenerative refrigerator of pulse tube type causes a gas piston in a pulse tube to reciprocate and expands a coolant gas in an expanded space and generates the cold in this process. The cold of the coolant gas generated in the expansion space is stored in the regenerator and is transferred to a cooling stage, which reaches a desired ultra-low temperature and cools a cooling object connected to the cooling stage.